Anyone done NIH GPP?

[starmaker]

Most of my prospective PhD programs are CS, but a couple are bioinformatics/bioengineering-type things, and I'm vaguely interested in the NIH Graduate Partnership Program (where you collaborate with an NIH scientist on your research, and the NIH pays your stipend). I've read the NIH GPP website, but there are still some things I don't understand. Mostly, I'm wondering how much time you have to spend physically at the NIH. Obviously, you'd be there often, as you're collaborating with one of their scientists, but is it something where you travel frequently but for short periods of time (e.g. a week every month), or is it something where you actually have to go live in DC for the whole time you're working on your dissertation? Or does that depend on your subfield and project and who you're working with (one might be able to work remotely on the computational side of bioinformatics work, for example, in a way that can't really be done with wet lab work)?

Has anyone done one of these (either institutional or individual)?